Patent GB-869735-A (GB)
Title: Lantern slide carrier system
IPC: G03B23/04
Filed: 1959-10-26
Abstract: 869,735. Optical projection apparatus. VIRET, R. E. J. Oct. 26, 1959 [Oct. 29, 1958; Feb. 18, 1959], No. 36229/59. Class 97(1) A lantern slide carrier system adapted to be fitted on a projection lantern has at least one filing drawer with a plurality of separate slidecarrying compartments from which a transverse slider with a magnetic head removes a slide, also' having a magnetizable part, to a projection area where means are provided for holding the slide in position, and further means produce advancement of the carrier by one compartment when slider arrives at the carrier for removal of a slide. As shown in Fig. 1 the carrier 10, detachably mounted on a projector 11, has two drawers 12 containing slides 13 which have a magnetizable portion 130. A slide is removed by a magnet 98 (Fig. 2) carried on a slider 54, having flexible blades engaging in an endless helical groove 52 on a motor rotated spindle 50 so that the slider is moved to register with an aperture gate 22. At the same time the magnet 98 moves a magnetic shutter 67 to close the projection aperture. The slide is held in projection position by projections 35 on a plate 30 which during registering of the slide have been constrained backwardly against spring loading by the engagement of a lug 32 with a tongue 97 of the slider. The slider progresses towards the end of the spindle leaving the slide in register, but moving the shutter 67 into engagement with an abutment to leave the projection aperture open. At the end of its movement a bar 100 on the slider engages the fork 105 of a lever 102 to push down member 108, whereby a pawl 117 turns a notched wheel 112 on the shaft of pinion 113 engaging a rack on the drawer 12 to move it along rails 83 by one slide-compartment space. A slide is then picked up by magnet 98, and the slider motion reverses at the end of the closed helical loop the bar 100 now pushing the fork 104 of lever 102 to prime the drawer feed mechanism. The new slide pushes the first one towards the right-hand drawer (where it originally came from) and is registered for projection in the manner previously described while the old slide is borne towards its compartment where a drawer feed mechanism (not shown) similar to that on the left-hand side is operated. During the drawer feed, the slider 54 is in register with the line of slides and is practically stationary while riding over the end loop of the helical groove so that the hold on the old slide is broken as the drawer moves on to present a further slide, and the cycle is repeated. During this change-over time, projection is taking place, and its duration depends on the pitch of the helical groove. At the end of its run, a lug 131 on the drawer engages a cut-out switch 132 to stop the motor 51. Alternatively several drawers may be connected in series, e.g. by means of magnets. For repetition of the same series of slides, the direction of drawer feed may be reversed at the end of each run by the engagement of a projection 134 on the carrier with a lever 136 carried on the feed lever 108 whereby said lever 136 is pivoted and reverses the slope of the rod 117 so that it will rotate wheel 112 in the opposite direction.